Resistance device



Jan. 15 1924. 1,480,645

A. E. WALLER RESISTANCE DEVICE Filed March 27 1922 Patented Jan. 15, 1924.

UNITED STATES I 1,480,645 PATENT OFFICE.

ALFRED ERNEST WALLER, F BRONXVILLE, NEW YORK, ASSIGNOR TO WARD LEONARD ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RESISTANCE DEVICE.

Application filed March 27, 1922. Serial No. 547,006.

To all whom it may concern: I

Be it known that I, ALFRED E. WALLER, a citizen of the United States, residing at Bronxville, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Resistance Devices, of which the following is a specification.

This invention relates to electrical re- 1 sistance devices, or rheostats, of the type wherein the resistor elements are of thin self-supporting strips, such as ribbon bent in the form of a channel.

. One object of the present invention is to provide a desirable form of connection, or support, at the ends of the resistor of the above type, or where connected to the contact segments, or at intermediate portions, and to do this not only so a good electrical connection with the resistor may be obtained, but also in such a manner as will give a rigid support to the resistor as well. Another object is to accomplish this result in a simple and convenient manner and to form a good electrical connection which will be durable and not likely to become loose or result in a poor contact with continued use. The securing of ample and permanent contact in this class of resistance devices is a matter of importance and difficulty, because these devices are adapted to carry comparatively large currents and if the contact is poor or insuflicient, a burn out results at the supporting joint, or contact connection.

Another object of this invention is to provide a form of construction of the resistors and their supports and relationship of parts, such that they will occupy a minimum amount of'space,.permit a simple and convenient form of construction and also make provision for ample dissipation of the heat generated in the resistors. Other objects and advantages of my invention will be understood from the accompanying drawings and 4 the following description:

Fig. 1 is an elevation of a bank of resistors on the back of a base board; Fig. 2 is a side view; Fig. 8 is an enlarged front view of the joint; Fig. 4 is an enlarged side View of the parts showing the joint and sup port and contact segments; Fig. 5 is an enlarged' side view of another support; and Fig. 6 is a perspective view of one of the resistor units.

In the embodiment of my invention shown in the drawings, the resistor is made from strips or ribbons of suitable resistant metal of the desired cross section. It is out 01f in lengths and bent into a channeled form as shown in Fig. 6, where the resistor element is shown in this instance as having three channeled portions 1 separated by intervening fiat portions 2. The ends 3 of the resistor are fiat and of the full width of the ribbon and form substantially square end portions. Each end portion has a hole 4.

Each resistor unit is bent at the so that the unit takes the form of a triangle and is here shown as an equilateral triangle approximately, as shown in Fig. 2. One end of the resistor is connected to one contact segment and the other end to an adjacent contact segment; at the latter segment another resistor element has one end connected thereto and its other end connected to the next segment, and so on.

A panel board or base 5 of insulating material forms a main support for the resistor elements and contact segments. The contact segments 6 are shown mounted on the front of the base board and secured in place by screw bolts 7. In this instance the contacts are arranged in two horizontal rows and bridged by a movable contactor 8 carried by a holder 9 guided in its movement by two parallel rods 10, so that by movement of the contact 8 any desired number of the resistor elements may be included or excluded from the circuit. I j

The joint connections of the resistor units to the contact segments and their support at the joint, is best shown in Figs. 3 and 4:. In making this joint and support, ends of adjoining resistor elements are clamped directly between twosquare metal washers 11. The size of these washers is preferably equal to or greater than the full width of the ribbon or strip from which the resistor is formed, that is, the washers preferably cover 1 the whole of the square end portions 3 of the resistor units. The screw 7 passes through contact segment 6 and the panel board and through the washers 11 and end portions of the resistor units, and on each side of the washers 11 is a nut 12 which firmly clamp the square washers and end portions of the resistor units together. A washer .13 is shown at the back of the panel board and between it and the inner nut 12 is shown a split spring washer 14.

portions 2 With this form of joint connection and support, there is secured an ample and firm contact between the ends of adjoining resistor elements and also between them and s the contact segments through the bolts 7 and even if the bolt 7 should become a little loose due to shrinkage of the panel board or other causes, the joint between the resistor elements and between them and the bolt 7 will always remain firm and always secure a good connection with the boltv 7 by reason of the washers and end portions of the resistor elements always being firmly clamped between the two nuts 12. But aside from the good electrical connection thus secured at the joint by the large square washers, these washers also serve to firmly and rigidly support the resistor elements at the joint. This is due to the fact that the Washers cover the end portions and extend to and along the full length of the line of the bend between the fiat portion 3 and main portion 1 oft-he resistor elements, and when thus supported, there is no chance of the elements twisting or bending out of place at this support; and even when heated, the support secured by this form of construction results in the resistor element remaining stiff and rigidly positioned at all times.

Referring to Figs. 1 and 2, there is preferably located at the outer apex of the triangle formed bythe rc.=istor elements, a common support such as a rod having a sleeve of insulating material thereon and around which the portions 2 of the resistor elements are located in circular form, and between which portions are insulating spacing washers 16. The other apex of the triangle located near the panel board is similarly supported by a common rod and insulating sleeve and spacing washers, but this part of the structure is also supported upon the panel or base board; and as the longitudinal expansion of the resistor elements is considerable, this support must be a flexible or yieldable one. In this instance, I have shown angular brackets 17 having one portion secured to the base as by a screw 18 and nut 19 and the other portion extending at right angles from the base and engaging and supporting the rod 15 at the apex of the resistor elements. This rod passes through a vertical slot 20 in the support-17, the nut 21 engaging the rod 15 on the outer side of the support 17. This nut however does not tightly engage the support 17 and the rod 15 is freely movable in the slot 20. Thus when expansion takes place in the portions of the resistors which are located near the panel board, the rod 15 can move in the slots 20 and thus permit expansion without interfering with the rigidity or eflective support of the resistor elements.

as i

In the present case there is shown an upper set of the triangularly formed resistor elements in parallel planes at right angles to the base or panel and having one leg of the triangle approximately parallel to the base and also a lower set similarly and reversely located. Each set is connected, as above described, to a row of supporting and conducting bolts 7 and to the row of contact segments 6, the two rows of segments being parallel to each other and bridged by the movable contactor 8.

In some cases only one row of contacts with its respective resistor elements may be used and the contacts maybe on a straight line or arc of a circle or otherwise arranged. The contact segments may sometimes be mounted on the same side of the base or panel as the resistors. The conducting and supporting bolt may of course be integral with the contact segment, and in some cases there may not be a contact segment, the bolt, screw or stud with the clamping means merely serving to support the resistors, or connect them with each other. The resistors, instead of being U shaped-as shown, may be otherwise channeled as by being ribbed lengthwise, or otherwise shaped to give stiffness between the supporting portions. Thus although I have illustrated and described a particular embodiment of my invention, the same is subject to various modifications without departing from the scope of my invention.

I claim:

1. In a resistance device, the combination of a ribbon resistor element having a flat supporting portion, a bolt passing through said portion, a rectangular washer of a size approximately equal to the width of said portion in contact therewith, and means on said bolt for clamping said rectangularwasher against said flat portion of the resistor element.

2. In a resistance device, the combination of a ribbon resistor element having a fiat supporting portion, a bolt passing through said portion. a rectangular washer of a size approximately equal to the width of said portion in contact therewith located on opposite sides of said portion respectively, and means on said bolt for clamping said washers against said fiat portion of the resistor element.

3. In a resistance device, the combination of a base, a conducting bolt passing therethrough, a contact segment connected to said bolt, a ribbon resistor element having a flat connecting portion through which said bolt passes, a rectangular washer of a size approximately equal to the Width of said portion and in contact therewith, and means on said bolt for clamping said rectangular washer against said flat portion of the resistor element. Y

at. In a resistance device, the combination of a base, a conducting bolt passin therethrough, a contact segment conneote to said bolt, a ribbon resistor element having a fiat connecting portion through which said bolt passes, a rectangular washer of a size approximately equal to the width of said portion and in contact therewith, located on opposite sides of said portion respectively, and means on said bolt for clamping said rectangular washers against said fiat portion of the resistor element.

5. In a resistance device, the combination of a base, a conducting bolt passing therethrough, a contact segment connected to said bolt, a ribbon resistor element having a fiat connecting portion through which said bolt passes, a rectangular washer of a size approximately equal to the width of said portion and in contact therewith, located'on opposite sides of said portion respectively, and a nut on each side of said washers respectively for clamping said washers againstextending along the line of the bend in said element between the main portion and the flat portion thereof, and means for holding said washer firmly against said flat portion.

7. In a resistance device, the combination of a ribbon resistor element having a flat supporting portion bent at an angle to the main portion of said element, and a support for said element comprising a bolt pass ing through said flat portion, a washer located on opposite sides of said flat portion respectively and each of said washers being approximately equal to the width of said flat portion and having an edge located at and extending along the line of the bend in said element between the main portion and the flat portion thereof, and means forholding said washers firmly against said fiat portion.

8. In a resistance device, the combination of a base, a row of supports on said base, a series of channel formed ribbon resistor elements connected to said supports, each of said resistor elements having at least two bent portions with intermediate straight portions and the ends of each of said resistor elements being connected to adjacent supports of said row respectively.

9. In a resistance device, the combination of a base, a row of supportson said base, a series of channel formed ribbon resistor elements connected to said supports, each of said resistor elements having at least two bent portions with intermediate straight portions and the ends ofeach of said resistor elements being connected to adjacent supports of said row respectively, and one of the straight portions of said resistor elements being approximately paralments from said base at one of said bent portions of each resistor element.

11. In a resistance device, the combination of a base, a row of supports on said base, a series of channel formed ribbon resistor elements connected to said supports, each of said resistor elements havin at least two bent portions with intermediate straight portions and the ends of each of said resistor elements being connected to adjacent supports of said row respectively, and means for yieldably supporting said resistor elements from said base at one of said bent portions of each resistor element.

12. In a resistance device, the combination of a base, a row of supports on said base, a series of channel formed ribbon resistor elements connected to said supports, each of said resistor elements having at least two bent portions with intermediate straight portions and the ends of each of said resistor elements being connected to adjacent supports of said row respectively and means for supporting said resistor elements from said base at the bent portion of each of said resistor elements which is near said base.

13. In a resistance device, the combination of a base, a row of supports on said base, a series of channel formed ribbon resistor elements connected to said supports, each of said resistor elements having at least two bent portions with intermediate straight portions and the ends of each of said resistor elements being connected to adjacent supports of said row respectively and means for yieldably supporting said resistor elements from said base at the bent portion of each of said resistor elements which is near said base.

14. In a resistance device, the combination of a base, a row of supports on said base, a series of channel formed ribbon resistor elements, each of said elements being bent in the form of a triangle and having its ends connected to adjacent supports respectively of said row.

15. In a resistance device, the combination of a base. a row of supports on said base, a. series of channel formed ribbon rellli sister elements, each of said elements being bent in the form of a triangle and having its ends connected to adjacent supports respectively of said row and one leg of the triangle being approximately parallel to said base.

16. In a resistance device, the combination of a base, a row of supports on said base, a series of channel formed ribbon. re- 

